This invention relates to a spring function component for a hydroelastic bearing.
Hydrostatic bearings can be used in a motor vehicle, for example. For example, a hydroelastic bearing can be used as a bearing for a cross member or a control arm, in particular a transverse control arm. In the case of its use as a cross member bearing, a system of a plurality of hydroelastic bearings, in particular four hydroelastic bearings, is provided, which are to be installed on the motor vehicle in four predetermined installation positions. When installed, the hydroelastic bearings of the system are aligned such that their axial directions correspond to a vertical line.
The hydroelastic bearing is generally used when a relative movement of a component such as a motor vehicle component that is subjected to an oscillating load relative to the vehicle body is to be permitted and damped. Because of the use of elastomer material, the hydroelastic bearing provides restoring spring forces as well as damping forces that are actively induced by means of dissipation losses inside the bearing.
Generally, the spring function component has an inner mounting connection by means of which the bearing is to be mounted on a component such as the vehicle body of a motor vehicle, which is subjected to an oscillating load. Another component, such as a motor vehicle component to be fastened to the motor vehicle body, is conventionally fastened to the spring function component by means of an outer mounting connection. A reversed connection of the spring function component to the motor vehicle body can also be considered. A spring body couples the mounting connections to one another in order to permit a relative mobility of the mounting connections. The spring body at least partly delimits two working chambers which are designed to receive a damping fluid. The working chambers can communicate hydraulically with each other via a choke channel to make possible an exchange of fluid between the working chambers at a predefined cross-sectional constriction to induce the dissipation losses through the flow between the working chambers. It is known that the damping characteristics can be defined by setting the flow resonance of the system of working chambers.
In the event of an excessively rapid relative movement between the inner mounting connection and the outer mounting connection, e.g. when the vehicle travels over a pothole, very high pressures can occur in one of the working chambers. This high pressure is caused by the fact that during impact loads of this type, the damping fluid cannot flow into the other working chamber fast enough via the choke channel. As a result, the spring function component of the hydroelastic bearing can burst open in the vicinity of the loaded working chamber.
To prevent a bursting of the spring function component in the event of an overload, the spring function component can include a pressure relief valve that opens when a defined pressure is exceeded in one of the working chambers and forms a hydraulic connection between the working chambers. However, it has been found to be difficult to correctly set the opening pressure of pressure relief valves of this type. Moreover, there have been problems with the manufacture of a pressure relief valve of this type.